By now, most of us know these bulbs will burn out quickly if they're turned on and off too frequently or placed in enclosed fixtures that don't let heat dissipate. But the same thing can happen if the bulb is installed upside down, with the ballast above the bulb. One theory is that excess heat from the bulb rises, potentially damaging the ballast components. "That's why many recessed CFL ceiling fixtures are designed with the bulbs oriented horizontally, not vertically," says Bergman, referring to U-shaped CFLs with prongs instead of screw-in bases. To avoid this potential pitfall, the Titlows chose fixtures with bulbs that are horizontal or upright.